Thread trimmer for sewing machines



April 23, 1929. J. KnEwlcz l THREAD' TRIMMER FORl SEWING MACHINES FledJan. 16, v1924 5 Sheets-Sheet 2 Fig.

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THREAD TEIMMER Fon SEWING MACHINES Filed Jan. 1e. 1924 5 shams-Sheet 4 Fig. 4 Fig. 5.

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April 23, 1929. J. Kll-:wlcz

THREAD TRIMMER FOR SEWING MACHINES Filed Jan. 16, 1924 5 sheets-sheet 5 v mgm Patented Apr. 23, 1929.

/UNITED STATES PATENT OFFICE.

JOHN'K'.EWICZ,` OF BOSTON', MASSACHUSETTS, ASSIGNOR T0 THE REECE BUTTON HOLE MACHINE COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION F MAINE.

THREAD TRIMMER Fon SEWING iviAcIIINI-is.y

Application filed January 16, 1924. Serial No. 686,626.

This invention relates to sewing machines of that type which are constructed to sew a short seam and then automatically come to rest, (a buttonhole sewing machine being an '5 exemplification of this type of Sewing'machine), and particularly to a device for trimming the under thread at the end ofthe sewing operation, and also the cord, if one is used in making 'the buttonhole. lo Buttonhole sewing machines are usually provided with Work-holding means and stitch-forming mechanism and some buttonv hole sewing machines are constructed so that when the machine comes to rest at the end of the sewing operation, the work-holding means and stitch-forming mechanism are properly situated relative to Aeach other for cuttingr the buttonhole slit, and when the machine is startedin operation the Workholding means and stitch-forming mechanism are rst given a relative movement to carry the parts from buttonhole-cuttingiposition to stitching position and then the stitch-forming mechanism is set in operation to form the edge stitches on the buttonhole and the parts have a further relative movement to feed the work during the stitching on the buttonhole. stitching on the buttonhole lhas been completed the stitch-forming mechanism is brought to rest `and the parts are given a further relative movement to carry them into buttonhole-cutting position.

In some se'wing machines the buttonhole is cut when the machine is first started in operation and before the stitching is performed and in other buttonhole sewing machines the cutting of the buttonhole takes place ust before the machine is brought to rest and after the buttonhole has lbeen stitched. Furthermore some buttonhole sewing machines are provided with means for laying a cord along the edge of the buttonhole as the stitching proceeds and one feature of the presenti invention relates to a novel mechanism which operates to cut not only the ,under thread but also the cord.

. AnotherI featuref the invention relates to an improveddevice for drawing olf a length of the under thread after the stitching on the buttonhole has been completed and before the cutting mechanism operates to cut said .thread and cord, the amount of thread thus-pulled `olf being suiicient to pro- When the4 -vide for the formation of the first stitch on the next fbuttonhole.

In order'to give an understanding of my invention I have illustrated in the drawings a .selected embodiment thereof which will now be described after which the novel features will be pointed out in the appended claims.

Fig. 1 irs/a si e view partially broken away of a portion of a's'ewing machine embodying my invention;

Fig. 2 is an under side view of the bed frame;

vFig

. bed frame on which the work is supported and showing the improved thread-cutting mechanism;

Fig. 4 is a view of the turret showing the lmeans for drawing off the under thread and' the cord; a

Fig. 5 is an edge View of the turret shown in Fig. 4;

Fig. 6 is a top plan view;

Fig'. 7 is a View showing the manner in which the pull-olf device operates;

Fig. 8 is a vertical sectional vview showing the position of the work and the threads fat the time the thread-cutting mechanism operates;

Fig. 9 is a `plan view of the thread-cutting device showing it -in thread-cutting position.

Fig. 10 is a fragmentary view of the cutting edges of the thread-cutting device.

While my invention is applicable to buttonhole sewing machines of various types I have chosen herein to illustrate it as it would `be applied to a buttonhole sewing machine of the well-known Reece type, exemplifi- 3 is a plan view of the portion of the cation of which maybe found in United States Patent No. 655,637, August 7 th, 190() and- No. 862,238, August 6th, 1907. `Such sewing machines are provided vwith Workholding means for holding the work and ynism may have any desirable construction beneath the work and mounted on a turret 5,

the latter having the throat plate 28 pro-t vided With an opening. In the sewing machine herein illustrated the needle 4 and the turret 5 supporting the under thread-handling mechanism are carried by a frame or head 6 which has the overhanging arm \7 in lwhich reciprocates the needle bar 8 carrying the needle 4 and which also has the turretsupporting portion .9 situated beneath the work and in which the turret 5 is rotatablymounted.

The lunder lthread-manipulating:, mechasuch'for instance Yasthat shown in either of said patents.-v That' herein shown is of the two looper variety illustrated in the above-mentioned Patent No. 862,238, August 6th, 1907, and it -comprises `two loopers 10 and 11 carried by an oscillating block 12 which is connected by a link 13 to a spindle 14 situated axially of the turret and recipro- A looper 10 is a thread-carrying looper, it

having an eye through which the under thread 24 is threaded, said thread passing through the sleeve 14 and around a suitable tension device 16 carried by theturret, all as usual in sewing machines of this type. Both the turret and the needle barr are mounted for rotary movement about a vertical axis to provide for stitching around the ends of the buttonhole, such movement being secured from the rock shaft 17 which has two ysegment 'gears 18 (only one of which is herein shown) that mesh with gears 19 and 20 on the needle bar holder and turret respectively.

In these sewing machines the stitch-forming mechanism and the Work-holding means have a relative movement, both during the stitching on the buttonhole and before and after the stitching and such relativemovement ma be provided for either by moving the wor -holding means relative tothe stitch-forming mechanism or moving the stitch-forming mechanismI relative to the Work-holding means. i .In the construction. herein shown the work-holding means are stationarily mounted on the bed plate 1 and the frame 6 which carries the .stitch-forming mechanism is mounted 'to move back and forth on the bed plate, but the invention which` is hereinafter described is equally applicable to. sewing machines in which the relative movement is produced by a movement of the work-holding means .rather-than of the frame 6.

21 indicates the usual buttonhole cutter` by Which-the buttonhole slit iscut. The relative movement between the stitch-forming l horizontally vplate as seen in Fig. 8.

mechanism and work-holding means is produced by means of the main cam 22 which is situated beneath the bed frame and this cam also actuates the buttonhole cutter 21 in proper timed relation. t

The parts thus far described are or may be all as usual in buttonhole sewing machines of this type and form no part of the present invention and inasmuch as their operation is well knowfn to those skilled in the art it will not be necessary to rehearse it here. t y l 'It may be brieiy stated, however, that when the machine comes to rest at the end of a buttonhole the work-holding means and stitch-forming mechanism are in the relative position shownY in full lines Fig. 1l with the needle 4 considerably in advance of the Y sewing point and with the work in buttonhole-cutting position. When the machine is started in operation the frame 6 with the stitch-forming mechanism moves backwardly to bring the needle into the dotted line position or into buttonhole-stitching position and at this time the shaft 23 for driving the stitch-forming mechanism is set in operation and the stitching on the buttonhole begins.

During the stitching the frame 6 continuesto move backwardly to cause the stitching to be formed down one side 'of the buttonhole and then moves forwardly to the dotted line position Fig. 1, thereby forming the stitches on the opposite side of the buttonhole. When the stitching is completed the stitchforming mechanism comes to rest and then the frame moves forwardly again to the position shownin Fig. 1, thus bringing lthe work into buttonhole-cutting position. 4The I buttonhole cutter is actuated while the Work is in buttonhole-cutting position and either after the stitching on the buttonhole is completed or beforethe stitching is started.

As stated above one feature of the present invention relates'to means for cutting the under thread 24 and the cord 25 at the end of the stitching operation. I/Vhen the stitching on Ithebuttonhole has been completed and the stitch-forming mechanism comes to rest the needle 4 will be in the dotted line position Fig. 1, the throatl plate 28 will be directly beneath the needle and in the dotvted line position Fig. 3, and the under thread 24.and cord 25 will extend-from the Work 'w directly downwardly through the throatplate'. When the frame 6 and stitch-forming mechanism move forwardly into the full line position' or into buttonhole-cutting position the throat plate will be carried into position shown in full lines in Fig. 3 and in Fig. 8 and a length of the under thread 24 and cord 25 will extend substantially from the werkte the throat My improved thread-cutting means is constructed to cut this horizontally-extending portion of the under thread and cord close to the work. The thread-cutting device comprises two co-operating cutting elements 26, 27 which are pivotally mounted so4 Fig. 10.

that they have a scissors-like action. These cutting elements are shown as secured to two blocks 29 and 30 which .are -pivotally mounted at 31 on the plate 32 carried by the` bed frame.

The block 29 is provided with an arm 33 and the block 3() is provided with a similar arm 34, the two arms extending parallelt0 cach other and being separated from each otl1er. Situated between the two armsA is a cam device 35, which is turnable about a vertical axis and which when turned clockwise in Fig. 3 acts against the arms 33 and 34 thereby spreading the same and closing the shearing members 26, 27 together. The two arms 33, 344 are connected by a spring 36, which tends to hold the shears open' in the position shown in Fig. 3. f v

The cutting or shearing edges of the cutting members 26, 27 extend substantially vertically and as the cam 35 operates to actuate the cutting members these cutting edges act on and sever 'the cord and under threadclose to the work. The construction is such that the cutting of the thread and cord is done by the upper portion) of the cutting edges and in order to obviate any possibility that the cord or thread will be crowded upwardly out of the shearing edges when they are brought into cutting position I will preferably make the shearing edges of substantially the shape. shown in The cutting member -26 is formed with a notch 81 in its upper edge which provides a horn or point 82 and the shearing edge 830i the member 27 ivsvpreferably' vformed on an inclination.

enl these shearing edges come together and move past each other the points 82 and 8470i the shearing edges will pass over the thread 24and cord 25 and prevent them from being forced upwardly out `from between the shearing edges. 'The notch81 forms a recess in which the thread and cord are received and retained during the thread-cutting operations thus preventing said cord and thread from being 'moved either'upwardly ordownwardly while .they are being cut. Furthermore since both of the cutting elements are pointed when they move toward each otherthe points will tend to crowd inl between the work and the horizontally-extending thread and stay` co'd and Athus-separate the' thread `and stay cord from the work, said thread .and stay cord being forced downwardly rather than upwardly and carried into the notch 81.

The cord 25 which is'used in buttonhole sewing machines is usually considerably larger and heavier than the under thread and in order to, successfully sever it' the The construction herein provided is positive in its action and will readily sever the heaviest cord which is used in buttonhole sowing machines.

The cam- 35 may be actuated by any'suitable means at the proper point in the cycle of operations. In' the construction herein shown this cam is actuated from the main' cam 22. For vthis purpose the cam 35 is mounted on a stud 37 which is journalled in the plate 32 and which projects below said plate, the projecting portion having` an arm 38 fast thereon which is engaged by the shoe portion 39 of a lever 40 whichv is ast'on a rock shaft 42 that is mounted in the housing 41 of the cam 22. This rock shaft has an arm 43 rigid therewith which is adapted to be engaged by a roll 44 that `is rigid with the main cam 22. For this purpose the main cam is provided with a hub 4e pension 45 carrying an arm 46 yon which the lroll 44 is mounted.

The roll is so positioned that thelatter will engage the arm 43 afterthe stitchforming mechanism has come to rest and just as the frame 6 'completes its movement by which the needle is carried .from the dotted to the full line position Fig. 1. 'lhe swing- 4.

ing of the arm 43 and lever 40 by the roll 44 operate .through the arm 38 to swing thecam 35. into' the position shown in Fig. 9, thereby closing the cutting elements 26, 27

and severing the under `thread 24 and thev of the shears cutting the workas well as the thread and cord I have pro- -vided a guard plate 47 'which is attached to the plate 32 and which -extends over the 4' shears. is prevented thereby from being4 drawn down into the path oishearing edges. A

The invention also comprises means acting of the latter from the source of supply before the cutting operation takes plac the purpose of ,this being to provide a su cient on the under thread 24 to draw off a'length.' )ust- The work rests onthis plate' 47 and lf Y '115 movement of .the Y length of thread to ensure the properormak tion of the first stitch when the stltching 0peration is begun'again.

The pulling o' of lcomplished by a pull-oit finger 48 which opcrates directly beneath the throat plate 28 he under thread is acturned so as to cause the pull-olf linger to swing across the throat `plate into the position shown in Fig. 7 thereby engaging the under thread 24 and drawing off a length thereof from the source of supply. This swinging movement of the pull-olf arm is herein secured by or through the rotationof the turret and the relative movement between the stitch-forming mechanismy and work-holding means by which the parts arel carried from stitching to buttonhole-cutting position. For this purpose the rock shaft 49 is provided at its lower end with a crank arm 71 having a crank pin .50 which is connected by a link 51 to a swinging lever 52 pivoted 'to the turret at 53 and acted on by a spring 54 which normally holds it in the position shown in Fig. 4, in which position the pull-off arm will bein the position shown in Fig.` 6. When the parts are in this posi- Y tion the outer edfe of the lever 52 stands outside of the edge 55 of the turret. A swinging movement of the'lever 52 inwardly will operate to give the pull-oil' arm 48 its thread-pulling movement. Such swing- .ing movement ofthe lever 52 is derived from la cam 56, which is carried on' an arm 57 secured to the bed frame.

In sewing machines of this type the turret is given a rotation to carry the stitching around the end of the buttonholey as the lbuttonhole is completed and when the stitchforming mechanism has been lbrought 'tol rest the frame 6 is moved forwardly to bring the parts into the buttonhole-ciitting position represented by the full lines Fig. 1. At this point the turret is given' a backward rota-- tion to bring it to its initial position. `When the stitching on the buttonhole Ais completed the turret has been turned into.aI position 180o from that shown in Fig. 2, in which position the lever 52 is on the same side of the turret as the cam 56. This is the position the turret occupies when the frame 6 is moved forwardly to carry the parts into buttonholecutting Aposition and during such forward movement the lever 52 engages and wipes by the cam 56 as shown in Fig. 7, thereby swinging the lever inwardly and through the link 51 and crank pin 50 giving the pullolfl lever 48 its thread-pulling movement into the position shown in Fi 7 .l As the lever 52 wipes by the high polnt of the cam 56'`r the pull-off lever will be allowed to back u slightly thus giving up some of thev threa This slack, however, is taken up by the forward movement of the turret and when the forward movement of the frame 6 is completed and the parts are in the positions shown in Figs. 1 and 8 the thread between the throat rg/lateand the work will be taut. The pull-oft' finger 48 still engages the thread at this time.v After the frame 6 has been brought to the limit of its forward movement and into buttonhole-cutting-'position the buttonhole cutter is actuated to cut the buttonhole (that is, provided the machine is of the type in which the buttonhole is cut after the stitching is completed,) and while the buttonhole is being cut the turret is given a backward rotation to bring it into the po-l sition sho-wn in Fig. 2. During such barkward rotation of the turret the lever 52 is carried out of engagement of the cam 56 and the pull-off arm 48 resumes its'normal position shown in Fig. 6 thereby giving up the thread which had been pulled olf.

The lever- 52 also functions to relieve the tension on the under thread and for this purpose the upper end 58 of the lever is adapted to enter between the disks of the tension 16 and spread the latter, this occurring at the same time that the. arm 48 has its thread-pulling movement.

I claim:

1. In avtwo-thread buttonhole sewing machine, the combination with work-holding means, of stitch-forming mechanism constructed to concatenate the upper and under threads to form the edge stitches along the buttonhole, a throat plate located closely below the work and through which the under thread is led to the work, means to give the stitch-forming mechanism and work-holding means relative horizontal feeding movements, and a further `relative movement after the but-tonhole is sewed, whereby a length of the under thread is drawn through the A throat plate and extends between the throat plate and the work in a substantially horizontal direction,` a pair` of relatively mova- -ble cutting elements pivotally mounted to turn about a common vertical axis 'which isl stationary relative to the work-holding means, one of which cutting elements is tathereafter to cut the thread/close to the 2. In a two-thread buttonhole sewing machine, the lcombination with work-holding means, of stitch-forming mechanism constructed to lay a cord alongthe edge of the buttonhole and to concatenate the upper and under threads to form the edge stitches along the buttonhole,A a throat plate located closely below thework and through'l which the under thread is led to the work, means to give the stitch-forming lnechanism-` and l which cutting elements is tapered toward its extremity, means actuating said cutting elements first tothrust the nose of said tapered element between the work and the horizontally-extending thread and cord after the buttonhole is completed, thereby to separate the thread and cord from the work and then to cut said thread and cord close to the Work. l

3. In a sewing machine, the combination withwork-holding means, of stitch-forming mechanism, a mam cam for producing a relative movement between the stitch-forming mechanism and work-holding means', means to cut the thread beneath the work comprising a pair of pivotally-mounted cutting elements each having an Aarm,' a lcam member situatedbetween said arms, a rock shaft carrying said cam member, and means associated with the main cam toY actuate the rock shaft. v l

4. In -a buttonhole sewing machine,l the combination with work-holding means, of-

stiteh-forming mechanism constructed to layv a cord along the edges of' the buttonhole and lform buttonhole stitches over the cord a main cam-'for vproducing a' relative movement between .the stitch formingmeehanism and work-holding means, of means to cut both ythe cord and the thread beneath the work,

said means comprising a pair of pivotallymounted cutting elements each having an arm, a cam member situated between said arms, a rock' shaft carrying vsaidv cam.1nember and means associated with the main cam to actuate the roclrshaft. Y

5. In a sewing machme, the combination with work-holding means, of stitch-forming `lmeclianism adapted to perform a predeterminedsewing operation 'and then come to rest, said stitch-forming mechanism including means for manipulating both the upper j and under threads, a turret on which the under thread-manipulating4 mechanism is mounted, a throat plate carried by the turret and through which the under lthread isled to hthe work, means to give the stitchforming mechanism and work-holding means a relative movement after the stitch-forming mechanism has i come to rest, whereby a length of under thread is drawn through the throat plate and extends from the work to the throat plate in a substantially horizontal direction, a pair 'of cutting elements co-axi ially pivoted to turn abouta commonvertical axis having a stationary position 'relative to the work-holding means, and cam' means Iacting on the cutting elements to cause them to turn about their common axis to cutthe thread close to ftle work.

-6. In a sewing machine, the combination with work-holding means, of stitch-forming mechanism adapted to perform a predetermined sewmg operationyand' then come to rest,`said stitch-'forming mechanism includi to the work, means to give the stitch-forming mechanism and work-holding means a relative movement after the stitch-forming mechanism has` come to rest, whereby a length/'of under thread is drawn through the throat plate and, extends from the work to i the throatplate in' a Substantially-horizontal direction, and cutting elements having substantially vertical cutting edges to out the thread close to the work.

l7. In a sewing machine, the combination with work-holding means, of stitch-forming mechanism adapted to perform a predetermined sewmg operation and then come -torest, said stitch-forming mechanism including'means for manipulating both the upper v a turret on which theand under threads,

ulatingv mechanism is under thread-mani and throu h whiihi'the-under thread is led to the wor means to ive the" stitch-forming mechanism and work tive movement vvafter lthe stitch-forming mechanism has come `to (rest, whereby ya length of under thread l,is drawn through the throat`plate andv extends from the work to l lthe throat plate in aysubstantially-horizontal direction, two cutting' elements pivoted to turn about a common vertical axis whichis stationarily mounted relative to the work- -holding means, each cutting element'having a substantially. vvertical cutting edge, .and

means to actuate s aid elements vto cut the thread close to the work. l 8. In a buttonhole sewing machine,` the combination with work-holding means, of. stitch-forming mechanism constructed to lay.

the -buttonhole and acord along the edge of v and under threads to concatenate theoupper to form the edge stitches mounted, athroatp atecarried by the turret olding means a rela- Y A4along thebuttonhole, a turret on which the' under thread- .x manipulting -mechanism is mounted, a

thread and cord is drawn through the throat plate and extends from the latter to the work in a substantially-horizontal direction, a pair of cutting elements situated beneath the work and pivoted to turn about a common vertical axis which is stationarily mounted relative to the work-holding means, and means to actuate said cutting elements to cut the under thread and cord close to the work. v

9. In a. buttonhole sewing machine, the combination with work-holding means, of stitch-forming mechanism constructed to lay a cord along the edge'of the buttonhole and to concatenate the upper and under'. threads to form the edge stitches along the bottonhole, a turret on which the under threadmanipulating mechanism is mounted, a throat plate carried by the turret and through which the under thread and cord are led to the work, means to give the stitchforming mechanismv and work-holding means av relative movement after tHe buttonhole is sewed, whereby., a length of under thread and cord is drawn through the throat plate and extends from the latter to the work in a substantially-'horizontal direction, and

thread-cuttingJ means having vertical shearing edges to cut the cord and thread close to the work.

l0. In a sewing machine, thecombination with work-holding means, of stitch-forming mechanism, a throat plate through which the thread is led to the work, means to give the stitch-forming mechanism and work- .holding means a relative feeding movement ...during the sewlng operation and a further relative movement after the sewing is completed, whereby a length of thread is drawn through the throat plate and extends between the throat plate and the work, a guard plate stationarily mounted relative to the work-holding means and situated in a plane between the work and the throat plate, a pair of relatively movable cutting elements operating beneath the guard plate, and means to actuate said elements after said further relative movement has been completed thereby to cut close to the work the length of thread extending from the work to the throat plate.

In testimony whereof, I have signed mv name to this specification.

JOHN KIEWCZ. 

